Ebola-infected doctor flown to US

The most recent Ebola patient to arrive in the United States is "extremely ill" and receiving "maximum" care to save his life, doctors say.

Martin Salia, a US resident infected with the deadly hemorrhagic fever while treating patients in his home country of Sierra Leone, was flown to the University of Nebraska Medical Center for treatment early on Sunday.

After a thorough examination, doctors said his condition was "extremely critical".

"This is an hour-by-hour situation," said Phil Smith, medical director of the biocontainment unit at UNMC, one of a handful of medical facilities in the United States specially designated to treat Ebola patients.

"He is extremely ill," Smith said, adding that experts were "targeting his most serious medical issues".

"We will do everything humanly possible to help him fight this disease."

There is no known cure for Ebola, one of the deadliest known pathogens, but trials for several possible treatments were announced this week in West Africa and Canada.

More than 5100 people are known to have died of the virus in West Africa and nearly 15,000 people have been infected in its deadliest ever outbreak - most in Liberia, Sierra Leone and Guinea.

Salia is the third Ebola patient to be treated by the UNMC. Both of the previous patients survived.